Nosocomial infections in an Iranian burn care center

Genomic and metabolic versatility of Pseudomonas aeruginosa contributes to its inter-kingdom transmission and survival

Pseudomonas aeruginosa is one of the most versatile bacteria with renowned pathogenicity and extensive drug resistance. The diverse habitats of this bacterium include fresh, saline and drainage waters, soil, moist surfaces, taps, showerheads, pipelines, medical implants, nematodes, insects, plants, animals, birds and humans. The arsenal of virulence factors produced by P. aeruginosa includes pyocyanin, rhamnolipids, siderophores, lytic enzymes, toxins and polysaccharides. All these virulent elements coupled with intrinsic, adaptive and acquired antibiotic resistance facilitate persistent colonization and lethal infections in different hosts. To date, treating pulmonary diseases remains complicated due to the chronic secondary infections triggered by hospital-acquired P. aeruginosa. On the contrary, this bacterium can improve plant growth by suppressing phytopathogens and insects. Notably, P. aeruginosa is one of the very few bacteria capable of trans-kingdom transmission and infection. Transfer of P. aeruginosa strains from plant materials to hospital wards, animals to humans, and humans to their pets occurs relatively often. Recently, we have identified that plant-associated P. aeruginosa strains could be pathologically similar to clinical isolates. In this review, we have highlighted the genomic and metabolic factors that facilitate the dominance of P. aeruginosa across different biological kingdoms and the varying roles of this bacterium in plant and human health.

Anti-Pseudomonas aeruginosa Vaccines and Therapies: An Assessment of Clinical Trials

Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen that causes high morbidity and mortality in cystic fibrosis (CF) and immunocompromised patients, including patients with ventilator-associated pneumonia (VAP), severely burned patients, and patients with surgical wounds. Due to the intrinsic and extrinsic antibiotic resistance mechanisms, the ability to produce several cell-associated and extracellular virulence factors, and the capacity to adapt to several environmental conditions, eradicating P. aeruginosa within infected patients is difficult. Pseudomonas aeruginosa is one of the six multi-drug-resistant pathogens (ESKAPE) considered by the World Health Organization (WHO) as an entire group for which the development of novel antibiotics is urgently needed. In the United States (US) and within the last several years, P. aeruginosa caused 27% of deaths and approximately USD 767 million annually in health-care costs. Several P. aeruginosa therapies, including new antimicrobial agents, derivatives of existing antibiotics, novel antimicrobial agents such as bacteriophages and their chelators, potential vaccines targeting specific virulence factors, and immunotherapies have been developed. Within the last 2-3 decades, the efficacy of these different treatments was tested in clinical and preclinical trials. Despite these trials, no P. aeruginosa treatment is currently approved or available. In this review, we examined several of these clinicals, specifically those designed to combat P. aeruginosa infections in CF patients, patients with P. aeruginosa VAP, and P. aeruginosa-infected burn patients.

Pseudomonas aeruginosa: Infections, Animal Modeling, and Therapeutics

Pseudomonas aeruginosa is an important Gram-negative opportunistic pathogen which causes many severe acute and chronic infections with high morbidity, and mortality rates as high as 40%. What makes P. aeruginosa a particularly challenging pathogen is its high intrinsic and acquired resistance to many of the available antibiotics. In this review, we review the important acute and chronic infections caused by this pathogen. We next discuss various animal models which have been developed to evaluate P. aeruginosa pathogenesis and assess therapeutics against this pathogen. Next, we review current treatments (antibiotics and vaccines) and provide an overview of their efficacies and their limitations. Finally, we highlight exciting literature on novel antibiotic-free strategies to control P. aeruginosa infections.

Mutations in AR or SRD5A2 Genes: Clinical Findings, Endocrine Pitfalls, and Genetic Features of Children with 46,XY DSD

OBJECTIVE

Androgen insensivity syndrome (AIS) and 5α-reductase deficiency (5α-RD) present with indistinguishable phenotypes among the 46,XY disorders of sexual development (DSD) that usually necessitate molecular analyses for the definitive diagnosis in the prepubertal period. The aim was to evaluate the clinical, hormonal and genetic findings of 46,XY DSD patients who were diagnosed as AIS or 5α-RD.

METHODS

Patients diagnosed as AIS or 5α-RD according to clinical and hormonal evaluations were investigated. Sequence variants of steroid 5-α-reductase type 2 were analyzed in cases with testosterone/dihydrotestosterone (T/DHT) ratio of ≥20, whereas the androgen receptor (AR) gene was screened when the ratio was <20. Stepwise analysis of other associated genes were screened in cases with no causative variant found in initial analysis. For statistical comparisons, the group was divided into three main groups and subgroups according to their genetic diagnosis and T/DHT ratios.

RESULTS

A total of 128 DSD patients from 125 non-related families were enrolled. Birth weight SDS and gestational weeks were significantly higher in 5α-RD group than in AIS and undiagnosed groups. Completely female phenotype was higher in all subgroups of both AIS and 5α-RD patients than in the undiagnosed subgroups. In those patients with stimulated T/DHT <20 in the prepubertal period, stimulated T/DHT ratio was significantly lower in AIS than in the undiagnosed group, and higher in 5α-RD. Phenotype associated variants were detected in 24% (n=18 AIS, n=14 5α-RD) of the patients, revealing four novel AR variants (c.94G>T, p.Glu32*, c.330G>C, p.Leu110=; c.2084C>T, p.Pro695Leu, c.2585_2592delAGCTCCTG, p.(Lys862Argfs*16), of these c.330G>C with silent status remained undefined in terms of its causative effects.

CONCLUSION

T/DHT ratio is an important hormonal criterion, but in some cases, T/DHT ratio may lead to diagnostic confusion. Molecular diagnosis is important for the robust diagnosis of 46,XY DSD patients. Four novel AR variants were identified in our study.

Epidemiology and etiology of blood stream infections in a Belgian burn wound center

BACKGROUND

Infections are a major cause of morbidity in burn patients. We aimed to investigate the epidemiology and antibiotic susceptibility of blood stream infections in order to gain a better understanding of their role and burden in our Burn Wound Center.

METHODS

This retrospective epidemiological investigation analyzed data derived from medical files of patients admitted to our Burn Wound Center having had at least one positive blood culture between 1 January and 31 December 2018. We focused on the prevalence of causative agents in blood stream infections in function of the time after injury and on their drug sensitivity.

RESULTS

Among the 363 patients admitted to our Burn Wound Center during the study period, 29 had at least one episode of blood stream infection. Gram-negative organisms accounted for 56,36% of the pathogens in blood stream infections, Gram-positives for 38,17%, and yeasts for 5,45%. Pseudomonas aeruginosa was the most common bacterium (20%), followed by Staphylococcus epidermidis (16.36%), Escherichia coli and Klebsiella pneumoniae (9,09% each). A third of the Gram-negative isolates were multidrug resistant. Gram-positive cocci were isolated from blood cultures at a median of 9 days after the injury, earlier than Gram-negative rods (median 15 days). The main sources of blood stream infections were the burn wounds, followed by infected catheters.

CONCLUSIONS

Multidrug resistant bacteria must be considered when selecting empirical antibiotic therapy in septic burn patients. In our center, we need to update our antibiotic guidelines, to review the hospital infection control measures and to introduce routine typing technology.

Inhibition of bacterial growth through LED (light-emitting diode) 465 and 630 nm: in vitro

Photobiomodulation has been used to inactivate bacterial growth, in different laser or LED protocols. Thus, the aim of this study was to verify the inhibition of Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli, in ATCC strains and bacteria collected from patients with skin burns, after irradiation with LED; 300 μl of saline solution with bacterial suspension was irradiated at a concentration of 0.5-0.63, by the McFarland scale, after five serial dilutions, with evaluation of pre- and post-irradiation pH and temperature control. The cultures were placed in a bacteriological incubator at 37 °C for 24 h for later counting of colony-forming units (CFU). Data were analyzed by Shapiro-Wilk tests and single-factor ANOVA, with Tukey post hoc (p < 0.05). Both wavelengths and energy densities tested showed inhibition of bacterial growth. The comparison of the irradiated groups (ATCC) with the control group showed the following: S. aureus and P. aeruginosa 465 nm (40 J/cm²) and 630 nm (50 J/cm²) and E. coli 465 nm (40 J/cm²) and 630 nm (30 J/cm²). Among the ATCC S. aureus groups, there was a difference for 630 nm (30 J/cm²) and 465 nm (30, 40, 50 J/cm²). The bacteria from the burned patients were S. aureus (30 and 50 J/cm²) and P. aeruginosa (50 J/cm²). We conclude that different bacterial strains were reduced into colony-forming units after LED irradiation.

Initial white blood cell count and revised Baux score predict subsequent bloodstream infection in burn patients: A retrospective analysis of severe burn patients from the Formosa color dust explosion of 2015

BACKGROUND

Infections are the most common complications among hospitalized severe burn patients. However, limited literature reports early effective predictors of bloodstream infections (BSI) among burn patients. This study aimed to identify cost-effective biomarkers and valuable clinical scoring systems in the emergency department (ED) for the prediction of subsequent BSI in mass burn casualties.

METHODS

In 2015, a flammable cornstarch-based powder explosion resulted in 499 burn casualties in Taiwan. A total of 35 patients were admitted at Taipei Veterans General Hospital. These severe burn patients (median total body surface area [TBSA] 54%) were young and previously healthy. We assessed the potential of various parameters to predict subsequent BSI, including initial laboratory tests performed at the ED, TBSA, and multiple scoring systems.

RESULTS

Fourteen patients (40.0%) had subsequent BSI. The most common causative pathogen was the Acinetobacter baumannii (Ab) group, mostly carbapenem resistant and associated with a poor outcome. The area under the receiver operating characteristic curve revealed that the revised Baux score, TBSA, and initial white blood cell count had excellent discrimination ability in predicting subsequent BSI (0.898, 0.889, and 0.821, respectively). The rate of subsequent BSI differed significantly at the cut-off points of revised Baux score >76, TBSA >55%, and WBC count >16,200/mm³.

CONCLUSION

The initial WBC count at the ED, TBSA, and revised Baux score were good and cost-effective biomarkers for predicting subsequent BSI after burn injuries.

High prevalence of imipenem-resistant and metallo-beta-lactamase-producing Pseudomonas aeruginosa in the Burns Hospital in Tunisia: detection of a novel class 1 integron

Pseudomonas aeruginosa is one of the most important causes of nosocomial infections, and its eradication is very difficult due to its multidrug resistance. The objective of the present study was to characterize the metallo-beta-lactamases (MBLs), integrons, OprD modifications and virulence factors of P. aeruginosa strains isolated from burn patients and to analyze their genetic relatedness by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Sixty-seven P. aeruginosa isolates were recovered from different clinical samples of burn patients hospitalized in the Intensive Care Burn Unit of the Centre de Traumatologie et des Grands Brulés (Ben Arous, Tunisia), and MBLs and alterations in porin OprD were analyzed among imipenem-resistant isolates. Class 1 and 2 integrons were studied by PCR and sequencing of corresponding variable regions. The presence of eight genes involved in the virulence of P. aeruginosa was investigated by PCR. Fourteen of the 36 imipenem-resistant P. aeruginosa (IRPA) isolates (38.8%) were MBLs producers and harbored the bla_VIM-2 gene, in all cases included into class 1 integrons. A new class 1 integron was identified (intI1-bla_OXA-10-aadB-bla_VIM-2-aadB-bla_OXA-10). Five sequence types were detected among IRPA isolates: ST1, ST112, ST238, ST308 and ST395. P. aeruginosa is a major nosocomial pathogen in patients suffering burns, and the spreading of multidrugs resistant and MBL-producing isolates should be controlled in burn units. Moreover, the implantation of infection control guidelines is crucial to decrease the morbidity and mortality of nosocomial infections due to multidrug resistant P. aeruginosa.

Multi-drug resistant Pseudomonas aeruginosa and Klebsiella pneumoniae circulation in a burn hospital, Tehran, Iran

Pseudomonas aeruginosa and Klebsiella pneumoniae are among the most important Gram-negative bacteria that can cause nosocomial infections, especially in burn patients. It is important to determine genetic relationships in different clinical specimens as well as between clinical and environmental specimens, which can aid in detecting the source of infection.

The aim of this study was to investigate multi-drug resistant Pseudomonas aeruginosa and Klebsiella pneumoniae spread in a burn hospital, Tehran, Iran. After identification, antibiotic susceptibility testing of all isolates was conducted according to the CLSI guidelines. Further, pulsed-field gel electrophoresis (PFGE) was performed for molecular typing.

97 clinical and 33 environmental specimens were collected. 40 (55%) clinical strains of P. aeruginosa and K. pneumoniae were highly drug resistant. PFGE findings showed similar genetic features to those seen in multi-drug resistant and/or extensively drug resistant P. aeruginosa and K. pneumoniae in clinical and environmental isolates. Inhibition of bacterial spread in the hospital can help to control health care-associated infection and subsequently decrease the morbidity and mortality in hospitalized patients, particularly immunocompromised populations such as burn patients.

Microbiology in burns patients with blood stream infections: trends over time and during the course of hospitalization

BACKGROUND

Bloodstream infections (BSI) are a major cause of mortality in burns patients. Knowledge of the microbiology is crucial to direct empirical therapy. We sought to determine the causative microorganisms and antibiotic resistance in burns patients with BSI.

METHODS

All consecutive BSI episodes in a tertiary hospital burns unit from 2000 to 2014 were included. The following three subperiods were compared: 2000-2004, 2005-2009 and 2010-2014. Changes in BSI occurring during early and late hospitalization periods were evaluated.

RESULTS

A total of 103 BSI episodes were included. The cumulative incidence was 2.4 episodes/1000 patient days. A positive trend in the frequency of Gram-negative BSI, especially in the upsurge of Pseudomonas aeruginosa and Klebsiella spp. BSI after 2004, was observed. The most common causative pathogens in early BSI were Gram-positive microorganisms. P. aeruginosa and Klebsiella spp. became the predominant aetiology in the fourth week of hospitalization and beyond. There was a progressive increase in imipenem-resistant P. aeruginosa over time (0%, 67%, 75% in 2000-2004, 2005-2009, 2010-2014, respectively) and during the hospital stay (50% vs. 85.7%, in <7 days-BSI vs. >30 days-BSI, respectively). A higher SOFA (Sepsis-related Organ Failure Assessment) score was associated with Gram-negative BSI versus non-Gram-negative BSI (median: 2.5 vs. 0; p = 0.041).

CONCLUSIONS

There is a changing trend in the types of pathogens causing BSI in burns patients over the 14-year period and during the course of hospitalization. The problematic increase in carbapenem-resistance highlights the need for new antimicrobial stewardship policies and antibiotic prescribing protocols.

Barriers to Surgical Care and Health Outcomes: A Prospective Study on the Relation Between Wealth, Sex, and Postoperative Complications in the Republic of Congo

BACKGROUND

Approximately thirty percent of the global burden of disease is comprised of surgical conditions. However, five billion people lack access to surgery, with complex factors acting as barriers. We examined whether patient demographics predict barriers to care, and the relation between these factors and postoperative complications in a prospective cohort.

METHODS

Participants included people presenting to a global charity in Republic of Congo with a surgical condition between August 2013 and May 2014. The outcomes were self-reported barrier to care and postoperative complications documented by medical record. Logistic regression was used to adjust for covariates.

RESULTS

Of 1237 patients in our study, 1190 (96.2 %) experienced a barrier to care and 126 (10.2 %) experienced a postoperative complication. The most frequently reported barrier was cost (73 %), followed by lack of provider (8.2 %). Greater wealth was associated with decreased odds of cost as a barrier (OR 0.72 [0.57, 0.90]). Greater wealth (OR 1.52 [1.03, 2.25]) and rural home location (OR 3.35 [1.16, 9.62]) were associated with increased odds of no surgeon being available. Cost as a barrier (OR 2.82 [1.02, 7.77]), female sex (OR 3.45 [1.62, 7.33]), and lack of surgeon (OR 5.62 [1.68, 18.77]) were associated with increased odds of postoperative complication. Patient wealth was not associated with odds of postoperative complication.

CONCLUSIONS

Barriers to surgery were common in Republic of Congo. Patient wealth and home location may predict barriers to surgery. Addressing gender disparities, access to providers, and patient perception of barriers in addition to removal of barriers may help maximize patient health benefits.

Collateral sensitivity between aminoglycosides and beta-lactam antibiotics depends on active proton pumps

BACKGROUND

Selection inversion is the hypothesis for antibiotic resistant inhabitation in bacteria and collateral sensitivity is one of the proposed phenomena for achievement of this hypothesis. The presence of collateral sensitivity associated with the proton motivation pump between the aminoglycosides and beta-lactam group of antibiotics is one of the examples of collateral sensitivity in some studies. The aim of this study was to demonstrate that collateral sensitivity between aminoglycosides and beta-lactam antibiotics associated with proton motivation pump may not be true in all cases.

METHODS

In this study, 100 Pseudomonas aeruginosa were surveyed. Gentamicin and imipenem-resistant strains were confirmed by disc diffusion method and MIC. Active proton motivation pumps were screened by pumps inhibitor. Semi-quantitative Real-Time PCR assay was used to confirm gene overexpression.

RESULTS

Seventy-six and 79 out of 100 strains were resistant to gentamicin and imipenem, respectively. Seventy-five strains were resistant to both gentamicin and imipenem. The results of proton pump inhibitor test showed the involvement of active proton motivation pump in 22 of 75 imipenem- and gentamicin-resistant strains. According to Real - Time PCR assay, mexX efflux gene was overexpressed in the majority of isolates tested.

DISCUSSION

The collateral sensitivity effect cannot explain the involvement of active proton motivation pumps in both imipenem and gentamicin-resistant strains simultaneously. Active and/or inactive proton pump in gentamicin-sensitive and/or resistant strains cannot be a suitable example for explanation of collateral sensitivity between aminoglycosides and beta-lactam antibiotics.

The clinical and microbiological characteristics of infections in burn patients from the Formosa Fun Coast Dust Explosion

BACKGROUND/PURPOSE

Bloodstream infection is a leading cause of mortality among burn patients. This study aimed to evaluate the risk factors, causative pathogens, and the relationship between bloodstream infections and other infections among burn patients from the Formosa Fun Coast Dust Explosion.

METHODS

This retrospective study evaluated the demographic and clinical characteristics, infection types, causative pathogen(s), and isolates' antibiotic susceptibilities from patients who were hospitalized between June 27 and September 31, 2015.

RESULTS

Fifty-eight patients were admitted during the study period (36 males, mean age: 22.6 years). The mean burned total body surface area (TBSA) was 40% for all patients. Eighteen (31%) patients with mean TBSA of 80% had 66 episodes of bloodstream infections caused by 92 isolates. Twelve (18.2%) episodes of bloodstream infections were polymicrobial. Acinetobacter baumannii (19, 20.7%), Ralstonia pickettii (17, 18.5%), and Chryseobacterium meningosepticum (13, 14.1%) were the most common pathogens causing bloodstream infections. A high concordance rate of wound cultures with blood cultures was seen in Staphylococcus aureus (3, 75%) and C. meningosepticum (8, 61.5%) infections. However, no Ralstonia isolate was found in burn wounds of patients with Ralstonia bacteremia. A high concordance rate of central venous catheter cultures with blood cultures was noted in Ralstonia mannitolilytica (5, 62.5%) and Chryseobacterium indologenes (3, 60%) infections. Approximately 21.1% of A. baumannii strains were resistant to carbapenem. All S. aureus isolates were susceptible to methicillin.

CONCLUSIONS

Waterborne bacteria should be considered in patients of burns with possible water contact. Empirical broad-spectrum antibiotics should be considered for patients who were hospitalized for severe sepsis, or septic shock with a large burn. Antibiotic treatment should be administered based on the specific pathogens and their detection points.

Carbapenem Susceptibility and Multidrug-Resistance in Pseudomonas aeruginosa Isolates in Egypt

Background

Resistant Pseudomonas aeruginosa is a serious concern for antimicrobial therapy, as the common isolates exhibit variable grades of resistance, involving beta-lactamase enzymes, beside native defense mechanisms.

Objectives

The present study was designed to determine the occurrence of Metallo-β- Lactamases (MBL) and Amp C harboring P. aeruginosa isolates from Suez Canal university hospital in Ismailia, Egypt.

Methods

A total of 147 P. aeruginosa isolates, recovered from 311 patients during a 10-month period, were collected between May 2013 and February 2014; the isolates were collected from urine, wound and sputum. Minimum inhibitory concentration (MIC) determined by agar dilution methods was ≥2 μg/mL for meropenem and imipenem. Identification of P. aeruginosa was confirmed using API 20NE. Metallo-β- Lactamases and Amp C were detected based on different phenotypic methods.

Results

Overall, 26.5% of P. aeruginosa isolates (39/147) were carbapenem resistant isolates. Furthermore, 64.1% (25/39) were MBL producers, these isolates were screened by the combined disc and disc diffusion methods to determine the ability of MBL production. Both MBL and Amp C harbored P. aeruginosa isolates were 28% (7/25). Sixty-four percent of P. aeruginosa isolates were multidrug resistant (MDR) (16/25). The sensitivity toward polymyxin, imipenem, norfloxacin, piperacillin-tazobactam and gentamicin was 99%, 91%, 88%, 82% and 78%, respectively. The resistance rate towards cefotaxime, ceftazidime, cefepime, aztreonam and meropenem was 98.6%, 86%, 71.4%, 34% and 30%, respectively.

Conclusions

Multidrug resistance was significantly associated with MBL production in P. aeruginosa. Early detection of MBL-producing P. aeruginosa and hospital antibiotic policy prescription helps proper antimicrobial therapy and avoidance of dissemination of these multidrug resistance isolates.

Tracing of false negative results in phenotypic methods for identification of carbapenemase by Real-time PCR

BACKGROUND

Carbapenemase production causes multi antibiotics resistant in Gram-negative bacteria. A simple rapid and accurate phenotypic test for detection of Gram-negative carbapenemase-producing bacteria is useful for the treatment of infections. The aim of this study was to track the negative results in carbapenemase phenotypic test by Real-time PCR.

MATERIALS AND METHODS

In this study, 161 imipenem resistant Gram-negative bacteria were surveyed. Modified Hodge Test (MHT), boronic acid (BA), EDTA and dipicolinic acid were used for detection of Klebsiella pneumoniae carbapenemase (KPC) and metallo-beta-lactamase (MBLs). Different phenotypic methods and PCR confirmation followed by Real-time PCR for determination of phenotypic false-negative results were used.

RESULTS

Our results indicated that 85, 51 and 112 strains were MHT, BA and dipicolinic acid positive, respectively. No synergistic effect was observed between imipenem and EDTA. Sixty-nine strains were confirmed as carbapenemase-producers according to the results of molecular tests. All of the isolates carried the gene and expressed carbapenemase.

CONCLUSION

Comparison between the results of phenotypic and genotypic methods showed that the phenotypic methods could be used as the primary screening and the PCR remains as the gold standard for detection of carbapenemase positive strains.

Virulence Gene Profiles of Multidrug-Resistant Pseudomonas aeruginosa Isolated From Iranian Hospital Infections

Background:

The most common hospital-acquired pathogen is Pseudomonas aeruginosa. It is a multidrug resistant bacterium causing systemic infections.

Objectives:

The present study was carried out in order to investigate the distribution of virulence factors and antibiotic resistance properties of Pseudomonas aeruginosa isolated from various types of hospital infections in Iran.

Patients and Methods:

Two-hundred and seventeen human infection specimens were collected from Baqiyatallah and Payambaran hospitals in Tehran, Iran. The clinical samples were cultured immediately and samples positive for P. aeruginosa were analyzed for the presence of antibiotic resistance and bacterial virulence genes using PCR (polymerase chain reaction). Antimicrobial susceptibility testing was performed using disk diffusion methodology with Müeller–Hinton agar.

Results:

Fifty-eight out of 127 (45.66%) male infection specimens and 44 out of 90 (48.88%) female infection specimens harbored P. aeruginosa. Also, 65% (in male specimens) and 21% (in female specimens) of respiratory system infections were positive for P. aeruginosa, which was a high rate. The genes encoding exoenzyme S (67.64%) and phospholipases C (45.09%) were the most common virulence genes found among the strains. The incidences of various β-lactams encoding genes, including bla_TEM, bla_SHV, bla_OXA, bla_CTX-M, bla_DHA, and bla_VEB were 94.11%, 16.66%, 15.68%, 18.62%, 21.56%, and 17.64%, respectively. The most commonly detected fluoroquinolones encoding gene was gyrA (15. 68%). High resistance levels to penicillin (100%), tetracycline (90.19%), streptomycin (64.70%), and erythromycin (43.13%) were observed too.

Conclusions:

Our findings should raise awareness about antibiotic resistance in hospitalized patients in Iran. Clinicians should exercise caution in prescribing antibiotics, especially in cases of human infections.

Antibiotic Resistance Pattern and Evaluation of Metallo-Beta Lactamase Genes Including bla- IMP and bla- VIM Types in Pseudomonas aeruginosa Isolated from Patients in Tehran Hospitals

Beta-lactamase producing strains of Pseudomonas aeruginosa are important etiological agents of hospital infections. Carbapenems are among the most effective antibiotics used against Pseudomonas infections, but they can be rendered infective by group B β-lactamase, commonly called metallo-beta lactamase. In this study, the antimicrobial sensitivity patterns of P. aeruginosa strains isolated from 9 different hospitals in Tehran, Iran, as well as the prevalence of MBLs genes (bla-_VIM and bla-_IMP) were determined. A total of 212 strains of P. aeruginosa recovered from patients in hospitals in Tehran were confirmed by both biochemical methods and PCR. Their antimicrobial sensitivity patterns were determined by Kirby-Bauer disk diffusion method. Following MIC determination, imipenem resistant strains were selected by DDST method which was followed by PCR tests for determination of MBLs genes: bla-_IMP and bla-_VIM. The results indicated that, in the DDST phenotypic method, among the 100 imipenem resistant isolates, 75 strains were MBLs positive. The PCR test indicated that 70 strains (33%) carried bla-_VIM gene and 20 strains (9%) harbored bla-_IMP. The results indicated that the extent of antibiotic resistance among Pseudomonas aeruginosa is on the rise. This may be due to production of MBLs enzymes. Therefore, determination of antibiotic sensitivity patterns and MBLs production by these bacteria, can be important in control of clinical Pseudomonas infection.

Gram negative wound infection in hospitalised adult burn patients--systematic review and metanalysis-

BACKGROUND

Gram negative infection is a major determinant of morbidity and survival. Traditional teaching suggests that burn wound infections in different centres are caused by differing sets of causative organisms. This study established whether Gram-negative burn wound isolates associated to clinical wound infection differ between burn centres.

METHODS

Studies investigating adult hospitalised patients (2000-2010) were critically appraised and qualified to a levels of evidence hierarchy. The contribution of bacterial pathogen type, and burn centre to the variance in standardised incidence of Gram-negative burn wound infection was analysed using two-way analysis of variance.

PRIMARY FINDINGS

Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter baumanni, Enterobacter spp., Proteus spp. and Escherichia coli emerged as the commonest Gram-negative burn wound pathogens. Individual pathogens' incidence did not differ significantly between burn centres (F (4, 20) = 1.1, p = 0.3797; r2 = 9.84).

INTERPRETATION

Gram-negative infections predominate in burn surgery. This study is the first to establish that burn wound infections do not differ significantly between burn centres. It is the first study to report the pathogens responsible for the majority of Gram-negative infections in these patients. Whilst burn wound infection is not exclusive to these bacteria, it is hoped that reporting the presence of this group of common Gram-negative "target organisms" facilitate clinical practice and target research towards a defined clinical demand.

Blood stream infections in patients in the burn intensive care unit

Background

The study on bacteremia helps empirically select the proper antibiotics before the results of culture test about causative pathogen. The purpose of this study is to investigate causative pathogen in bloodstream infection, changing aspects based on elapsed time after burn, relationship with other sites and resistance of important causative pathogen against antibiotics through analysis on bacteria isolated from blood culture of patients hospitalized in burn intensive care unit (BICU).

Materials and Methods

A retrospective study was conducted targeting patients hospitalized in BICU from January 2007 to June 2011. Changes of causative pathogen in bloodstream infection based on elapsed time after injury were analyzed. We would like to examine the relationship between bloodstream infection and infection on other body parts by comparing results of cultures in burn wound site, sputum, urine and catheter tip. Antibiotics resistance patterns of Pseudomonas aeruginosa, Acinetobacter baumannii, Staphylococcus aureus, Enterococcus species, and Klebsiella pneumoniae were studied.

Results

A total of 2,337 burn patients were hospitalized in BICU for 54 months. Causative pathogen was cultured in blood cultures from 397 patients (17.0%). P. aeruginosa (169, 30.1%) was the most cultured and A. baumannii (107, 19.0%) and S. aureus (81, 14.4%) were followed. It was confirmed that the relative frequency of A. baumannii tended to get lower as the period got longer after injury, but the relative frequency of K. pneumoniae got higher as the period got longer after injury. With comparison without bacteremia, P. aeruginosa bacteremia showed high probability in which the same bacteria were cultured in wound site, sputum and cathether tip, and A. baumannii bacteremia and candida bacteremia had high probability in sputum, and urine and catheter tip, respectively. 95.9% of P. aeruginosa and 95.3% of A. baumannii showed the resistance against carbapenem. 96.3% of S. aureus was methicillin resistant and 36.2% of Enterococcus species were vancomycin resistant. 75.0% of K. pneumonia were extended-spectrum beta-lactamase (ESBL)-producing bacteria.

Conclusions

Since the highly antibiotic resistant microorganisms were isolated from the patients hospitalized in BICU during early phase, the empirical selection of antibiotics targeting these pathogens should be considered before the results of microbiologic culture test. In addition, use of empirical antifungal agent after 1 week of injury can be considered for patients who have risk factor of fungal infection.

Antimicrobial susceptibility of bacterial isolates from burn units in Gaza

BACKGROUND

Bacterial infections continue to be a leading cause of morbidity and mortality among burn patients despite intensive prophylaxis and treatment. Often treatment is complicated by the emergence of antimicrobial resistance pathogens. There are no reports or published data on the susceptibility profiles of bacteria isolated from burn patients in the Gaza strip.

PATIENTS AND METHODS

A cross sectional study was performed in the two burn units of Al-Shifa and Naser hospitals for 6 months from October 2010 to March 2011. A total of 118 wound samples from burn patients, 97 environmental samples and 28 samples from health care workers (HCWs) were collected and cultured according to the standard microbiological procedures. The bacterial isolates were identified by conventional methods and the antibiotic susceptibility profiles were determined by the standard disc diffusion method according to CLSI guidelines.

RESULTS

The overall percentage of positive cultures from both hospitals was 45.8%, where Nasser burn unit revealed higher positive cultures than Al-Shifa burn unit. Pseudomonas aeruginosa was the most common pathogen isolated (50%) followed by Enterobacter cloacae (28.3%). Meanwhile, fingers and nasal samples that collected from HCWs showed 78.6% and 32.3% positive cultures respectively, where P. aeruginosa was the highest pathogen isolated (32.3%), followed by Coagulase Negative Staphylococci (CoNS) (29%). Environmental samples also showed higher isolation rate of Pseudomonas and CoNS. Pseudomonas isolates from patients samples were found to be resistant to most of antimicrobials used except for piperacillin-tazobactam. The family Enterobacteriaceae isolated from patients and environmental samples were resistant to most of the tested antimicrobials. However, the Enterobacteriaceae isolates from HCWs samples were sensitive to the most of the tested antimicrobials. The incidence of methicillin-resistant Staphylococci according to oxacillin sensitivity test was 60% in patient's samples, 77.8% in HCWs samples and 90% in environmental samples.

CONCLUSION

High percentage of resistance was found among clinical isolates in general to the commonly used antibiotics with a notable increase in MRSA incidence among both patients and environmental samples as well as HCWs.

Epidemiology of infections in a burn unit, Albania

BACKGROUND

Many types of nosocomial infections (NIs) can be present in the burned patient. The purpose of this study is to calculate the rates for NI in the Intensive Care Unit of the Service of Burns and Plastic Surgery in University Hospital Centre (UHC) in Tirana, Albania.

METHOD

The study is prospective, clinical and analytical. The study is continued/longitudinal because monitors all patients with severe burns during a specified time period (1year). For data analysis was used SPSS 19.0.

RESULTS

The infection prevalence rate was 12 infected patients per 100 patients. The colonisation prevalence rate was 43 colonised patients for 100 patients. The most frequent infection microorganisms were Pseudomonas aeruginosa and Staphylococcus aureus (67% and 24%). Incidence of BSI was 3 BSI for 1000 hospitalization days. Incidence of catheter-related bloodstream infection (CRBSI) was 11.7 BSI for 1000 catheter days. Colonisation of the tip of the central catheter (CTC) was 15.6 for 1000 catheter days.

CONCLUSIONS

The epidemiology of burn wound infections as well as the definitions have changed due to important changes in burn wound treatment but further studies should be done documented the factors that can reduce the burn wound infection rates.

Three-year review of bacteriological profile and antibiogram of burn wound isolates in Van, Turkey

The risk of infection in burns is well-known. In recent decades, the antimicrobial resistance of bacteria isolated from burn patients has increased. For this reason, a retrospective study was conducted at Van Training and Research Hospital to analyze the bacterial isolates from the wounds of patients admitted to the Burn Unit and to determine the susceptibility patterns of the commonly cultured organisms over a 3-year period, January 2009 to December 2011.A total of 250 microorganisms were isolated from burn wounds of 179 patients. Our results revealed that the most frequent isolate was Acinetobacter baumannii (23.6%), Pseudomonas aeruginosa (12%), Staphylococcus aureus (11.2%), Escherichia coli (10%) respectively. Multidrug-resistance has emerged as an important concern in our burn unit. Tigecycline, and colistin were found to be the most active drugs against Acinetobacter baumannii. Carbapenems and amikacin, were found to be the most active drugs against other gram negative bacteria. Vancomycin and linezolid were active against gram positive bacteria.Aggressive infection control measures should be applied to limit the emergence and spread of multidrug-resistant pathogens.

Infection control in severely burned patients

In the last two decades, much progress has been made in the control of burn wound infection and nasocomial infections (NI) in severely burned patients. The continiually changing epidemiology is partially related to greater understanding of and improved techniques for burn patient management as well as effective hospital infection control measures. With the advent of antimicrobial chemotherapeutic agents, infection of the wound site is now not as common as, for example, urinary and blood stream infections. Universal application of early excision of burned tissues has made a substantial improvement in the control of wound-related infections in burns. Additionally, the development of new technologies in wound care have helped to decrease morbidity and mortality in severe burn victims. Many examples can be given of the successful control of wound infection, such as the application of an appropriate antibiotic solution to invasive wound infection sites with simultaneous vacuum-assisted closure, optimal preservation of viable tissues with waterjet debridement systems, edema and exudate controlling dressings impregnated with Ag (Silvercel, Aquacell-Ag). The burned patient is at high risk for NI. Invasive interventions including intravenous and urinary chateterization, and entubation pose a further risk of NIs. The use of newly designed antimicrobial impregnated chateters or silicone devices may help the control of infection in these immunocomprimised patients. Strict infection control practices (physical isolation in a private room, use of gloves and gowns during patient contact) and appropriate empirical antimicrobial therapy guided by laboratory surveillance culture as well as routine microbial burn wound culture are essential to help reduce the incidance of infections due to antibiotic resistant microorganisms.

The impact of the types of microorganisms isolated from blood and wounds on the results of treatment in burn patients with sepsis

Despite development of combustiology, infections continue to be the most important cause of death among patients with burns. Sepsis is the most severe clinical presentation of infection in patients after thermal injuries who require immediate treatment. Early diagnosis and proper treatment of sepsis are important in the clinical management that is often hampered for multiple reasons, e.g. impaired patient immunity, problems with microorganisms with multi-antibacterial drug resistance. The aim of the study was to assess effect of type of a microorganism isolated from blood and wound on results of treatment of sepsis in patients with burns.

MATERIAL AND METHODS

Effect of type of microorganisms isolated from blood and wound on the result of treatment of sepsis was studied in 338 patients hospitalized immediately after an injury in Centre for Burn Treatment in Siemianowice Śląskie in years 2003 - 2004 (at the age of 18 - 96 years, 66 women and 272 men). Clinical symptoms of generalized infection were found in all study subjects. The study group was divided into two subgroups: cured patients and patients who died of sepsis. The following parameters were assessed in both subgroups: type of microorganism isolated from blood, type of microorganism isolated from wound as well as occurrence of the same and different infections of blood and burn wound.

RESULTS

positive blood cultures were found in 165 patients (48.8%), 106 (64.2%) were cured, 59 (35.8%) died. The most commonly isolated microorganisms in cured patients were Gram(+) Staphylococcus epidermidis MRSE (19.81%) and Staphylococcus aureus MRSA (18.87%). Gram(-) intestinal rods were least commonly isolated from this group. The most commonly isolated microorganisms from blood of patients who were to die, included non-fermenting Gram(-) rods Acinetobacter baumannii (35.59%) and Pseudomonas aeruginosa (22.03%). Mixed bacterial flora was found in the blood of 22.03% patients. Among patients who were to die, the same microorganisms were found in the blood and in the wound in 32.2% of patients, while this rate was 17.92 in cured patients. The most commonly found bacteria in the blood and burn wound in the cured patients included Staphylococcus aureus MRSA (31.58%) and Staphylococcus aureus (21.05%). In the group of patients who were to die, the most common bacteria isolated simultaneously from the blood and burn wound included Acinetobacter baumannii (47.37%) and Pseudomonas aeruginosa (36.84%).

CONCLUSIONS

1. The patients with thermal injuries are at higher risk of death in the event of sepsis caused by Gram(-) bacteria versus Gram(+) bacteria. 2. Infection of blood and burn wound caused by the same bacteria Pseudomonas aeruginosa and Acinetobacter baumanni increases the risk of death due to sepsis in patients with burns following thermal injuries.

Nosocomial infections in burned patients in motahari hospital, tehran, iran

Burn patients are at high risk of developing nosocomial infection because of their destroyed skin barrier and suppressed immune system, compounded by prolonged hospitalization and invasive therapeutic and diagnostic procedures. Studies on nosocomial infection in burn patients are not well described. The objective of the present study was to identify the causative bacterial of nosocomial infection and to determine the incidence of nosocomial infection and their changing during hospitalization in burned patients admitted to in the Motahari Hospital, Tehran, Iran. During the second part of 2010, 164 patients were included in this study. Samples were taken the first 48 hours and the fourth week after admission to Motahari Burn hospital. Isolation and identification of microorganisms was performed using the standard procedure. Of the 164 patients, 717 samples were taken and 812 bacteria were identified, 610 patients were culture positive on day 7 while 24 (17.2%) on 14 days after admission. The bacteria causing infections were 325 Pseudomonas, 140 Acinetobacter, 132 Staphylococcus aureus, and 215 others. The percentage of mortality was 12%. All of patients had at least 1 positive culture with Pseudomonas and/or with Acinetobacter. Hospitals suggest continuous observationof burn infections and increase strategies for antimicrobial resistance control and treatment of infectious complications.

Simple, effective and affordable approach for the treatment of burns infections

OBJECTIVE

The aim of the present study was to develop a simple and effective treatment modality using citric acid as a sole antimicrobial agent to control infections in burns patients not responding to conventional treatment.

METHODS

Forty-six cases with 5-60% superficial to deep burns in a study group and 20 cases with 10-70% superficial to deep burns in a control group were investigated for culture and susceptibility. The isolates in study group were further tested for susceptibility to citric acid. Three percent citric acid gel was applied to burns wounds in study group; however, the control group received conventional antibiotic therapy and local wound care.

RESULTS

In the control group, Pseudomonas aeruginosa (44.44%) and Staphylococcus aureus (33.33%) were found to be the commonest bacterial isolates and, amikacin and ciprofloxacin (40.74%) were found to be most effective antibacterial agents. In study group, P. aeruginosa (30.48%) and S. aureus (23.17%) were found to be the commonest bacterial isolates. Ceftazidime (52.43%), ciprofloxacin (47.56%) and amikacin (46.34%) were found to be most effective antibacterial agents. Application of citric acid to burn wounds resulted in complete healing in 40 (86.95%) cases in 7-25 applications (P value 0.145); however, in a control group conventional antibiotic therapy and local wound care resulted in complete healing in nine (45%) patients only.

CONCLUSIONS

Citric acid treatment was found effective in the control of burns infections as compared to conventional therapy. Complete healing in 86.95% cases as compared to 45% in a control group indicates that citric acid is nontoxic, economical and quite effective in the management of burns infections.

Self-inflicted burn injuries in southwest Iran

Self-inflicted burns are among the most devastating of all burn injuries with serious physical, psychological, and financial effects on the individual, the patient's family, and society. This study was carried out to analyze the epidemiology, mortality, and current etiological factors of burn patients who were admitted to a major burn center in the Fars province. In a longitudinal prospective design, from April 2003 to March 2005, all burn patients that were admitted to Ghotb-eddin Shirazi Hospital were evaluated. Data in regard to patients' social demographics, burn injury, and outcome measures were collected. Suicide attempts by burning accounted for 231 (24.8%) of all burn patients admitted to hospital. Suicidal burns occurred predominantly in the age group 15 to 24 years (49.1%). Most (71.4%) self-burning cases were female. Deliberate self-burn patients have significantly larger burned body surface area than accidental burn patients [70% (4-100) vs 28% (1-100); P < .0001]. The case fatality rate for self-inflicted burns (62.3%) was significantly higher than the 27.7% rate observed for accidental burns (P < .0001). Burned body surface area >40% and self-inflicted burns strongly and independently predicted mortality. Self-inflicted burns continue to be a major health problem in this region. Special burn preventive programs should be implemented in primary health care system. A National Committee for Injury and Burn Prevention and Control should be established urgently to coordinate all burn prevention programs and collaborate between different sectors of the society.

The impact of nosocomially-acquired resistant Pseudomonas aeruginosa infection in a burn unit

BACKGROUND

Nosocomially-acquired Pseudomonas aeruginosa remains a serious cause of infection and septic mortality in burn patients. This study was conducted to quantify the impact of nosocomially-transmitted resistant P. aeruginosa in a burn population.

METHODS

Using a TRACS burn database, 48 patients with P. aeruginosa resistant to gentamicin were identified (Pseudomonas group). Thirty-nine were case-matched to controls without resistant P. aeruginosa cultures (control group) for age, total body surface area, admission year, and presence of inhalation injury. Mortality and various morbidity endpoints were examined, as well as antibiotic costs.

RESULTS

There was a significantly higher mortality rate in the Pseudomonas group (33% vs. 8%, p < 0.001) compared with in the control group. Length of stay was increased in the Pseudomonas group (73.4 +/- 11.6 vs. 58.3 +/- 8.3 days). Ventilatory days (23.9 +/- 5.4 vs. 10.8 +/- 2.4, p < 0.05), number of surgical procedures (5.2 +/- 0.6 vs. 3.4 +/- 0.4, p < 0.05), and amount of blood products used (packed cells 51.1 +/- 8.0 vs. 21.1 +/- 3.4, p < 0.01; platelets 11.9 +/- 3.0 vs. 1.4 +/- 0.7, p < 0.01) were all significantly higher in the Pseudomonas group. Cost of antibiotics was also significantly higher ($2,658.52 +/- $647.93 vs. $829.22 +/- $152.82, p < 0.01).

CONCLUSIONS

Nosocomial colonization or infection, or both, of burn patients with aminoglycoside-resistant P. aeruginosa is associated with significantly higher morbidity, mortality, and cost of care. Increased resource consumption did not prevent significantly higher mortality rates when compared with that of control patients. Thus, prevention, identification, and eradication of nosocomial Pseudomonas contamination are critical for cost-effective, successful burn care.

Analysis of anaerobic blood cultures in burned patients

The utility of anaerobic blood culturing is often debated in the general population, but there is limited data on the modern incidence, microbiology, and utility of obtaining routine anaerobic blood cultures for burned patients. We performed a retrospective review of the burned patients electronic medical records database for all blood cultures drawn between January 1997 and September 2005. We assessed blood cultures for positivity, organisms identified, and growth in aerobic or anaerobic media. 85,103 blood culture sets were drawn, with 4059 sets from burned patients. Three hundred and forty-five single species events (619 total blood culture isolates) were noted in 240 burned patients. For burned patients, four isolates were obligate anaerobic bacteria (all Propionibacterium acnes). Anaerobic versus aerobic culture growth was recorded in 310 of 619 (50.1%) burned patient blood culture sets. 46 (13.5%) of the identified organisms, most of which were not obligate anaerobic bacteria, were identified from solely anaerobic media. The results of our study suggest that the detection of significant anaerobic bacteremia in burned patients is very rare and that anaerobic bottles are not needed in this population for that indication. However anaerobic blood cultures systems are also able to detect facultative and obligate aerobic bacteria; therefore, the deletion of the anaerobic culture medium may have deleterious clinical impact.

The epidemiology, pathogenesis and treatment of Pseudomonas aeruginosa infections

Pseudomonas aeruginosa is an important bacterial pathogen, particularly as a cause of infections in hospitalised patients, immunocompromised hosts and patients with cystic fibrosis. Surveillance of nosocomial P. aeruginosa infections has revealed trends of increasing antimicrobial resistance, including carbapenem resistance and multidrug resistance. Mechanisms of antimicrobial resistance include multidrug efflux pumps, ss-lactamases and downregulation of outer membrane porins. Mechanisms of virulence include secreted toxins and the ability to form biofilms. The effective treatment of infections caused by P. aeruginosa includes prevention when possible, source control measures as necessary and prompt administration of appropriate antibacterial agents. Antibacterial de-escalation should be pursued in patients with an appropriate clinical response, especially when antibacterial susceptibilities are known. Multidrug-resistant P. aeruginosa may require treatment with less commonly used antibacterials (e.g. colistin), but newer anti-pseudomonal antibacterials are expected to be available in the near future.

Nosocomial infections in a Brazilian Burn Unit

In 1-year prospective study, bacterial and fungal infections presenting in burned patients were registered. Two-hundred and seventy-eight patients were included. The median total body surface area burned was 14% (range 1-100%). The median length of hospital stay was 12 days (range 1-86 days). Eighty-six patients had in all 148 infections. Seventy-two bloodstream infections (BSI) occurred in 57 patients; most common microorganisms were coagulase-negative staphylococci and methicillin-sensitive Staphylococcus aureus. Forty-nine (17.6%) patients had burn wound infections and 18 (6.5%) had pneumonia. Antibiotics were given to only 30% of the burn patients. Overall mortality rate was 5.0% (14/278). The database can be used to evaluate the effects of changes in burn treatment, staffing and design of burn units, and antimicrobial resistance development in relation to antibiotic usage.

Infection in acute burn wounds following the Bali bombings: a comparative prospective audit

INTRODUCTION

Bacterial colonisation and invasive bacterial infection remain the major causes of mortality and morbidity following severe burn thus ongoing surveillance of patients and monitoring of infection facilitates early intervention to minimise the risk of sepsis. The circumstances of the Bali bombings in October 2002, provided an opportunity to analyse the ramifications of lengthy transfer times, delayed resuscitation and topical treatment, on the primary incidence of burn wound infection (BWI).

METHOD

This prospective clinical audit investigated the primary incidence of BWI between the usual burn patients admitted to the Burn Unit at Royal Perth Hospital, Western Australia, and a number of survivors from the Bali bombings during a 3-month audit period in 2002. BWI was identified using the Peck et al. proposed definitions for the surveillance of burn wound infections. These include impetigo, surgical wound related infection, cellulitis and invasive infection of unexcised wounds.

RESULTS

The incidence of primary BWI in the Bali-tourist group (68.2%) compared with the standard WA group (18.2%) was significant (p=0.001).

CONCLUSION

Sensitive assessment criteria allowed for early identification of wound infection. A clinically significant difference in the Bali-tourist group is probably related to the circumstances of their injury.

Review of statistical data about severe burn patients treated during 2001 and evidence of septic cases in Albania

The objective of this study is to review the incidence of severe burns and the complications of burns sepsis in Albanians. The data are from clinical records of the patients hospitalised in the intensive care unit (ICU) of the Service of Burns, "Mother Teresa" University Hospital Center (UHC), Tirana, Albania during 2001. For the identification of sepsis in burned patients the classification of the American College of Chest Physicians/Society Critical Care Medicine (ACCP/SCCM) was used. All the cases were evaluated according to the clinical, diagnostic and laboratory data. The study presents some epidemiological data about the causative agent, the extent of burn, the depth of burn and the subjects injured. The study also identifies the pathogens responsible for the development of sepsis among patients. Such data was used to establish compound therapies focused on two or three antibiotics for each subject in order to treat sepsis and its possible complications. As a most important part of the treatment regime it is essential to identify patients at risk of sepsis, and to apply compound therapy with antibiotics in order to resist and treat this sepsis, which is the main cause of high mortality among our severely burned patients.

Aerobic bacterial isolates from burn wound infections and their antibiograms--a five-year study

A retrospective study of major aerobic bacterial isolates from pus/wound swabs taken from patients admitted to the burn unit at Govt. Medical College Hospital, Chandigarh, India, over a period of 5 years (June 1997-May 2002) was undertaken. The study was carried out to determine the bacterial profile and antimicrobial susceptibility of the isolates and to describe the change in trends over the study period. The pus/wound swabs yielded very high culture positivity (96%) for 665 total isolates. Pseudomonas aeruginosa was found to be most common isolate (59%) followed by Staphylococcus aureus (17.9%), Acinetobacter spp. (7.2%), Klebsiella spp. (3.9%), Enterobacter spp. (3.9%), Proteus spp. (3.3%) and others (4.8%). Although P. aeruginosa continued to remain the predominant isolate over the five years, a constant and significant increase in the incidence of Acinetobacter spp. was found. Amikacin was found to be the most effective drug against gram negative bacteria, however, resistance to it was significantly increased over 5 years. For S. aureus and P. aeruginosa netilmicin and piperacillin were found to be the most effective drugs. Most of the isolates showed high level resistance to antimicrobial agents.

Sepsis in burned patients

A prospective study was conducted from June 2001 to May 2002 at the Burns Unit of Hospital Regional da Asa Norte, Brasília, Brazil. During the period of the study, 252 patients were treated at the Burns Unit, 49 (19.4%) developed clinically and microbiologically proven sepsis. Twenty-six (53.1%) were males and 23 (46.9%) females with a mean age of 22 years (range one to 89 years) and mean burned body surface area of 37.7 +/- 18.4% (range 7 to 84%). Forty-three patients had flame burns, five a scald and one an electric burn. These 49 patients had a total of 62 septic episodes. Forty (81.6%) patients had only one and nine (18.4%) had up to three episodes of sepsis. Thirty (61.2%) patients had their first septicemic episode either earlier or by one week postburn. Out of 62 septic episodes, 58 were due to bacteria and four due to Candida sp. The most common bacteria isolated from blood culture were Staphylococccus aureus, coagulase-negative Staphylococcus, Acinetobacter baumannii, Enterobacter cloacae and Klebsiella pneumoniae. Eleven (18.9%) episodes were due to oxacillin resistant Staphylococcus aureus. Acinetobacter baumannii was sensitive to ampicillin/sulbactam in 71.4% and to imipenem in 85.7% of the cases. The primary foci of sepsis were the burn wound in 15 (24.2%) episodes. The most common clinical findings of sepsis in these patients were fever, dyspnea, hypotension and oliguria. The most common laboratory findings of these patients were anemia, leukocytosis, hypoalbuminemia and thrombocytopenia. Twelve (24.5%) patients died. The appropriate knowledge of clinical, epidemiological, laboratorial and microbiological aspects of sepsis in burned patients permits an adequate diagnosis and treatment of this complication.

Pseudomonas infections in the thermally injured patient

Pseudomonas aeruginosa, remains a serious cause of infection and septic mortality in burn patients, particularly when nosocomially acquired. A prototypic burn patient who developed serious nosocomially acquired Pseudomonas infection is described as an index case which initiated investigations and measures taken to identify the source of the infection. The effect of changes in wound care to avoid further nosocomial infections was measured to provide data on outcome and cost of care. The bacteriology of Pseudomonas is reviewed to increase the burn care providers understanding of the behaviour of this very common and serious pathogen in the burn care setting, before reviewing the approach to detection of the organism and treatment both medically and surgically. After controlling the nosocomial spread of Pseudomonas in our burn unit, we investigated the morbidity and mortality associated with nosocomial infection with an aminoglycoside resistant Pseudomonas and the associated costs compared to a group of case-matched control patients with similar severity of burn injury, that did not acquire resistant Pseudomonas during hospitalization at our institution. We found a significant increase in the mortality rate in the Pseudomonas group compared to controls. The morbidity in terms of length of stay, ventilator days, number of surgical procedures, and the amount of blood products used were all significantly higher in the Pseudomonas group compared to controls. Costs associated with antibiotic requirements were also significantly higher in the Pseudomonas group. Despite this increased resource consumption necessary to treat Pseudomonas infections, these efforts did not prevent significantly higher mortality rates when compared to control patients who avoided infection with the resistant organism. Thus, in addition to the specific measures required to identify and treat nosocomial Pseudomonas infections in burn patients, prevention of infection through modification of treatment protocols together with continuous infection control measures to afford early identification and eradication of nosocomial Pseudomonas infection are critical for cost-effective, successful burn care.

Incidence of urinary tract and bloodstream infections in Ghotbeddin Burn Center, Shiraz 2000-2001

Though burn wound infections have been extensively studied, other nosocomial infections (NIs) in burn patients have received less attention. Invasive diagnostic procedures (vascular and bladder catheterization) make the burn patients more susceptible to different nosocomial infections. The aim of this study was to determine the rate of bloodstream and urinary tract infections associated with i.v. line and urinary catheter (UC) in Ghotbeddin Burn Center and also to compare these rates with those of the National Nosocomial Infections Surveillance System (NNIS) in the USA. This study was conducted over 11 months, from 21st December 2000 to 21st November 2001. All the patients who were admitted for more than 48 h and did not have evidence of infection at the time of admission were included in the study. For diagnosis of urinary tract and bloodstream infections, the standard definitions from the Center for Diseases Control (CDC) were used. Of the total 106 qualifying patients, 91 study patients acquired nosocomial infections (85.85%). Urinary catheter-associated urinary tract infection (UC-UTI) rate was 30 per 1000 urinary catheter days and i.v. line-associated bloodstream infection (i.v. line-BSI) rate was 17 per 1000 i.v. line days. Comparison of incidence rates of UC-UTI and i.v. line-BSI in Ghotbeddin Hospital and NNIS showed that rate of infection to be higher in Ghotbeddin Hospital while device utilization ratio (urinary catheter and central line) was higher in the NNIS hospitals. To reduce the rate of infection at Ghotbeddin Burn Center, education, development of standardized guidelines for the use of invasive devices and introduction of a nosocomial infections surveillance system are necessary.

Modification of in vivo and in vitro T- and B-cell-mediated immune responses by the Pseudomonas aeruginosa quorum-sensing molecule N-(3-oxododecanoyl)-L-homoserine lactone

N-3-(oxododecanoyl)-L-homoserine lactone (OdDHL), a quorum-sensing molecule of Pseudomonas aeruginosa, plays an important role in the pathogenesis of the organism through its control of virulence factor expression. Several reports have suggested that OdDHL can also directly modulate host immune responses. However, the nature of the modulation is controversial, with different reports suggesting promotion of either humoral (Th2-mediated) or inflammatory (Th1-mediated) responses. This report describes a series of studies which demonstrate for the first time that in vivo administration of OdDHL can modulate the course of an antibody response, with an increase in ovalbumin (OVA)-specific immunogloblulin G1 (IgG1) but not IgG2a in OdDHL-treated OVA-immunized BALB/c mice compared to levels for controls. In vitro stimulation of lymphocytes from both Th1-biased C57Bl/6 and T-cell receptor transgenic mice and Th2-biased BALB/c mice in the presence of OdDHL demonstrated that OdDHL inhibits in vitro cytokine production in response to both mitogen and antigen, with gamma interferon (IFN-gamma) tending to be more inhibited than interleukin-4 (IL-4). In vitro mitogen or antigen restimulation of cells from mice treated with OdDHL in vivo shows effects on cytokine production which depend on the underlying immune bias of the mouse strain used, with a relative increase of IFN-gamma in Th1-biased C57Bl/6 mice and a relative increase of IL-4 in Th2-biased BALB/c mice. Thus, the mode of action of OdDHL on T-cell cytokine production is likely to be a relatively nonspecific one which accentuates an underlying immune response bias rather than one which specifically targets either Th1 or Th2 responses.